New [ONOO]-Type Amine Bis(phenolate) Ytterbium(II) and -(III) Complexes: Synthesis, Structure, and Catalysis for Highly Heteroselective Polymerization of <i>rac</i>-Lactide
ion in both complexes adopts a distorted octahedron. All the complexes synthesized together with the known YbII complex 3 were evaluated in the ring-opening polymerization (ROP) of rac-lactide (rac-LA). Complexes 1 and 4 were found to be extremely active for controlled ROP of rac-LA, as judged by narrow molar mass distributions (Mw/Mn: 1.07–1.16 for complex 1 and 1.07–1.10 for complex 4) and experimental
通过Yb II(N(SiMe 3))的胺消除反应以高收率合成了由新的[ONOO]型胺双酚盐配体L a,b支撑的两个二价(Yb II)配合物1和2。2)2(TMEDA)(TMEDA =四甲基乙二胺),其中一当量的配体前体。X射线结构测定表明配合物1和2均具有单体结构。每个都围绕六坐标Yb II离子采用扭曲的八面体配位几何形状。两种新的三价(Yb III)芳氧化物配合物,参照图4和图5,通过Yb(C 5 H 5)3 THF与一当量的配体前体,然后一当量的Nb(C 5 H 5)3 THF的双质子化反应制备带有[ONOO]型胺双(酚盐)配体L c和L d。苯酚。配合物4具有对称的二聚体结构,其Yb 2 O 2核通过OC 6 H 4 -4-CH 3基团的氧原子桥接。配合物5是THF溶剂化的单体。每个六个配位的Yb III两种配合物中的离子均采用扭曲的八面体。在rac-丙交酯(rac -LA)的开环聚合(ROP)中评估了与已知的Yb